Add configurable registration wait strategy

[MisonL]

Summary

• add a persisted global wait strategy for batch registration: start or completion
• apply the selected strategy to pipeline scheduling and expose the active mode in settings and registration UI
• add focused tests and a review record for the new behavior

Verification

• docker exec codex-console-dev-webui-1 python -m pytest tests/test_settings_registration_auto_fields.py tests/test_registration_wait_strategy.py -q
  • 6 passed in 1.91s
• python3 runtime check on http://127.0.0.1:16666/login and http://127.0.0.1:15555/login
  • both returned 200
• coderabbit review --prompt-only --base upstream/main -t committed
  • Review completed: No findings

Notes

• verification record: docs/reviews/CR-REGISTRATION-WAIT-STRATEGY-2026-04-02.md
• formal service on 15555 was not modified during dev verification